Why do some people have a severe allergic reaction to a drug while others have no reaction at all? This is based on a person’s genotype, which influences how the body metabolizes drugs. While individual genetic variants, or the genetic makeup of each individual, play a large role in the development of diseases and somatic responses to drugs, other factors that affect how a person’s body responds to drugs include lifestyle factors such as drug and alcohol use, environmental factors such as exposure to radiation and chemicals, and physiological factors such as gender, age, and liver function (Ahmed, Zhou, Zhou & Chen, 2016).
The body’s response to a drug, referred to as pharmacodynamics, depends on how long it takes for the body to absorb, metabolize and excrete the prescribed drug. The body produces enzymes that break down a drug, changing its chemical structure to make it easier for the body to excrete the medication.
The efficacy (and toxicity) of the drug depends on the speed at which the body metabolizes a certain medication. For some, their bodies may metabolize the drug too quickly before it has a chance to work at effective levels. For others who take the same medication, their bodies might metabolize too slowly, which means that toxins can build up in the body, causing a range of reactions from mild to life-threatening somatic responses.
The aim of pharmacogenetic testing is to avoid life-threatening reactions by using information that could help health care professionals predict treatment outcomes. Patients who are on multiple medications on a regular basis, or those who have had adverse reactions to a drug that resulted in hospitalization, may benefit from pharmacogenetic testing.
In addiction treatment, patients who have comorbid disorders such as substance use disorders, mental health disorders, and physiological disorders may be at risk for adverse reactions if they are taking multiple medications to address each health issue. Results derived from drug-gene testing can inform health care professionals about the appropriate medicine and dosage for a patient and possibly predict whether the patient will have a severe reaction to a certain drug.